Phthalocyanine analogs

ABSTRACT

Disclosed are compounds of formula V  
                 
 
     where M is a metal atom; a metal compound; 2H whereby one H is bonded to each of the two nitrogen atoms depicted as being bonded to M (positions 29 and 31 shown) R 3  is H or methyl; R 1  and R 4  are independently selected from: H, C 1  to C 4  alkyl, C 2  to C 4  alkenyl, methoxy, butoxy, propoxy, NH 2 , NH—(C 1  to C 4  alkyl), N—(C 1  to C 4  alkyl) 2 , S—(C 1  to C 4  alkyl); R 8  to R 25  are the same or different and are independently selected from: C 1  to C 32  alkyl; C 2  to C 32  alkenyl; X—O—Y; X-phenyl, X 2 COOX 1 , X 2 CONR 1 R 11 , H; halide; where: X and X 2  are independently selected from: a chemical bond, —(CH 2 ) n — where n is an integer from 1 to 32, —(CH 2 ) a —CH═CH(CH 2 ) b  where a and b are independently selected from integers 0-32 and a+b totals 32; X 1  and Y are independently selected from: C 1  to C 32  alkyl, C 2  to C 32  alkenyl, and H; R 1  and R 11  are independently selected from: H; C 1  to C 32  alkyl, C 2  to C 32  alkenyl, —(CH 2 ) n —; with the proviso that at least one of R 8  to R 25  is selected from: C 1  to C 32  alkyl, C 2  to C 32  alkenyl, X—O—Y, X-phenyl, X 2 COOX 1 , X 2 CONR 1 R 11 .

[0001] The present invention relates to phthalocyanine analogs, inparticularly to azaphthalocyanines (pyridinoporphyrazines). It furtherrelates to compositions containing these compounds, and methods of useof such compounds and compositions.

[0002] Phthalocyanine is shown in FIG. 1(a). The nomenclature for thenumbering of the Benzo portion is also included in the above depiction.Generally substituents in the R2, 3, 9, 10, 16, 17, 23, 24 positions arereferred to as peripheral groups and substituents in the R1, 4, 8, 11,15, 18, 22, 25 positions are referred to as non-peripheral groups.

[0003] Often, phthalocyanine is abbreviated to Pc.

[0004] Pcs in condensed phases possess interesting optical absorptionsignatures, semiconductivity and optoelectronic properties which areoften sensitive to molecular packing. Normally, the planar molecules areprone to form co-facial or near co-facial assemblies. These“Face-to-Face” structures include the simple aggregates found insolution,² the longer columnar stacks in the liquid crystal phases ofmesogenic derivatives.³ and the classic “herring bone” columnar packingin the most common polymorphs of the unsubstituted compounds.⁴ Polymericcolumnar structures include the “shish-kebab” polymers formed when thecentral metal atoms of neighbouring Pc units are covalently orcoordinatively linked via bridging atoms or molecules.⁵

[0005] The unusual properties that Pcs and Pc analogs exhibit means theyhave many applications.

[0006] UK Patent GB 2,229,190 B relates to certain novel substitutedphthalocyanines, methods for their preparation and to certain usesthereof. For example the compounds described in GB 2,229,190 B aresuitable for use in optical recording media. Kuder in J. of ImagingScience, vol. 32, (1988). pp51-56 discusses how phthalocyanine dyes maybe used in laser addressed optical recording media, in particular itsets out how active layers may be deposited.

[0007] UK Patent Application 9317881.2 describes substitutedmetallophthalocyanines and phthalocyanines as PDT agents.

[0008] Patent application WO 93/09124 describes the use of water solublesalt or acid forms of transition metal phthalocyanines for use inphotodynamic therapy. In this patent application, phthalocyaninescontaining second or third row transition metals with a d6 low-spinelectronic configuration are disclosed. The compounds exemplified inpatent application WO 93/09124 contain Ru.

[0009] Phthalocyanine derivatives have also been used in LangmuirBlodgett films as described in UK Patent 2,229,190 B.

[0010] The redox behaviour of phthalocyanines is also of interest. Someuses which exploit the redox properties of phthalocyanines includeelectrocatalysis, photocatalysis, photovoltaics, electric conduction,photoconductivity and electrochromism. These uses (amongst others) ofphthalocyanines are discussed by A. B. P. Lever in Chemtech, 17,pp506-510, 1987.

[0011] Certain pyridinoporphrazines (azaphthalocyanines, or AzaPcs)havebeen prepared and reported in the literature. These includetetrapyridino derivatives and bipyridino derivatives having Cr, Co, Cu,Fe and Ni centres. Thus Linstead⁷ first demonstrated the replacement ofall four benzene rings of the Pc nucleus by pyridine in his classicinvestigations in the 1930s, obtaining a mixture of insoluble isomericdyes from 3,4-dicyanopyridine. Subsequently, Shibamiya and coworkersprepared unsubstituted inacrocycles containing combinations of bothbenzenoid and pyridinoid rings.⁸ The absorption spectra of thesecompounds were described, although not with reference to any particularapplications.

[0012] It can thus be seen that the provision of novel Pc derivatives(or uses for such derivatives) particularly those with novel absorptionsignatures, would provide a contribution to the art.

DISCLOSURE OF THE INVENTION

[0013] The present inventors have now produced and characterised novelorganic solvent-soluble AzaPcs in which a pyridinoid ring isincorporated in or around the Pc nucleus. Such compounds provide, interalia, for the generation of “Edge-to-Face” assemblies via metal-nitrogencoordination involving the pyridyl nitrogen atom of one molecule and themetal ion of a second molecule.

[0014] Although Edge-to-Face assembles have been constructed earlierusing porphyrin derivatives,⁶ they have not as yet been realised withinthe Pc series. Such compounds have unexpected and industriallyapplicable properties in a variety of technical fields as is describedin further detail hereinafter.

[0015] Thus according to one aspect of the invention there is disclosedan AzaPc of Formula I (FIG. 1(b)):

[0016] wherein:

[0017] M is selected from:

[0018] a metal atom; a metal compound, 2H whereby one H is bonded toeach of the two nitrogen atoms depicted as being bonded to M (positions29 and 31 shown)

[0019] and wherein:

[0020] one or more of the Q groups is selected from: formula II orformula III, with the remaining Q groups each being formula IV:

[0021] wherein:

[0022] R₃₃ and R₃₄ are independently selected from: H or methyl

[0023] R₃₅ is selected from: H; C₁ to C₄ alkyl; C₂ to C₄ alkenyl;methoxy; butoxy; propoxy; NH₂; NH—(C₁ to C₄ alkyl); N—(C₁ to C₄ alkyl)₂,S—(C₁ to C₄ alkyl).

[0024] each R_(n) and R_(p) group is independently selected from: C₁ toC₃₂ alkyl: C₂ to C₃₂ alkenyl; X—O—Y; X-phenyl

[0025] X²COOX¹; X²CONR¹R¹¹; H; halide

[0026] wherein:

[0027] X and X² are independently selected from: a chemical bond,—(CH₂)_(n)— wherein n is an integer from 1 to 32;—(CH₂)_(a)—CH═CH(CH₂)_(b) where a and b are independently selected fromintegers 0-32 and a+b totals 32.

[0028] X¹ and Y are independently selected from: C₁ to C₃₂ alkyl; C₂ toC₃₂ alkenyl; H

[0029] R¹ and R¹¹ are independently selected from: H; C₁ to C₃₂ alkyl;C₂ to C₃₂ alkenyl; —(CH₂)_(n)—

[0030] with the proviso that where more than one Q is Formula II withthe remaining Q group being Formula IV, at least one of the R₃₃, R₃₄,R₃₅, R_(n), or R_(p) groups is not H.

[0031] In a further, preferred aspect of the invention, there isdisclosed an AzaPc having formula V (FIG. 1(f)).

[0032] Wherein:

[0033] M is selected from:

[0034] a metal atom; a metal compound; 2H whereby one H is bonded toeach of the two nitrogen atoms depicted as being bonded to M (positions29 and 31 shown)

[0035] R₃ is H or methyl

[0036] R₁ and R₄ are independently selected from: H; C₁ to C₄ alkyl: C₂to C₄ alkenyl; methoxy; butoxy; propoxy; NH,; NH—(C₁ to C₄ alkyl); N—(C₁to C₄ alkyl)₂, S—(C₁ to C₄ alkyl).

[0037] R₈ to R₂₅ are the same or different and are independentlyselected from:

[0038] C₁ to C₃₂ alkyl; C₂ to C₃₂ alkenyl; X—O—Y; X-phenyl X²COOX¹;X²CONR¹R¹¹; H halide

[0039] wherein:

[0040] X and X² are independently selected from: a chemical bond:—(CH₂)_(n)— wherein n is an integer from 1 to 32:—(CH₂)_(a)—CH═CH(CH₂)_(b) where a and b are independently selected fromintegers 0-32 and a+b totals 32.

[0041] X¹ and Y are independently selected from: C₁ to C₃₂ alkyl; C₂ toC₃₂ alkenyl; H

[0042] R¹ and R¹¹ are independently selected from: H; C₁ to C₃₂ alkyl;C₁ to C₃₂ alkenyl; —(CH₂)_(n)—

[0043] Most preferably the compound has formula VI (as shown in FIG.1(g), wherein M=2H, Ni, Zn, Co, Cu, Pd, Ru or Al.

[0044] Referring to formula I, formula VI has one Q group of formula IIwith the remaining Q groups each being formula IV, R₃₃, R₃₄ and R₃₅ areH; R_(n) are C₈ alkyl and R_(p) is H.

[0045] Preferred Compounds

[0046] Preferred compounds of the present invention are those whereinany one or more of the following apply:

[0047] All non-peripheral R groups (e.g. R_(n) in formula III and IV)are H.

[0048] All R groups other than those attached to pyridyl nuclei arealkyl containing up to 32 (preferably up to 20, more preferably between4-14 or between 8-12) C atoms where 1 or more adjacent CH₂ groups may bereplaced by O or a double bond, and the remaining R groups are all H.

[0049] All peripheral R groups other than those attached to pyridylnuclei are alkyl containing up to 32 (preferably up to 20, morepreferably between 4-14 or between 8-12) C atoms, and the remaining Rgroups are all H.

[0050] The R groups attached to the or each pyridyl nucleus on the Catoms adjacent the N (i.e. R₃₃, R₃₄, R₁, R₃ as appropriate) are H,thereby minimising steric hindrance in those embodiments of theinvention which form “edge-to-face” dimers or higher oligomers.

[0051] The R group attached to the or each pyridyl nucleus which is inthe meta-position with respect to the N (i.e. R₃₅ or R₄ as appropriate)is an electron donating group thereby increasing the basicity of the Nsuch as to enhance its properties as a ligand.

[0052] Examples of this type of group include O-alkyl, NH₂, NH-alkyl,N(alkyl)₂, alkyl, S-alkyl.

[0053] In all cases the alkyl groups may be straight or branched chain.Straight chain are preferred.

[0054] The compounds of the invention may be metal free or contain ametal bound to a ligand (such compounds may have utility, inter alia, inthe manufacture of metal containing derivatives, for instance asintermediates) or may contain a metal atom, preferably a diamagneticmetal atom.

[0055] The metal atom may be present for example as the metal with anoxidation state of +2 or it may be present with other ligands (oranions) attached to it. These ligands (or anions) may serve the purposeof altering the hydrophobicity of the molecule as a whole. Examples ofsuitable anions include chloride, bromide or oxide. Examples of suitablemetals include Ru, Ni, Pb, V, Pd, Co, Nb, Al, Sn, Zn, Cu, Mg, Ca, In,Ga, Fe, Eu, Lu and Ge. Preferably when M is a metal or metal compoundthen the metal is, or the metal compound contains Cu, Zn, Ru, Pb, V, Co,Eu, Lu, Al. Examples of suitable metal compounds include V0 and TiO.Those which may preferentially form “edge-to-face” dimers or higheroligomers under appropriate conditions include Zn, Cu, Co, Ru, and Ni.

[0056] Applications

[0057] Methods of use of the compounds described above form furtheraspects of the present invention. Some particular applications areexemplified below:

[0058] PDT

[0059] In this application it is preferred that M in the compounds ofthe present invention is diamagnetic e.g. a second or third rowtransition metal with a d⁶ low-spin electronic configuration, preferablyZn. Ru-containing compounds may also be advantageous.

[0060] A number of Pc derivatives have previously been proposed aspotential photodynamic therapeutic (PDT) agents. The combination of asensitizer and electromagnetic radiation for the treatment of cancer iscommonly known as photodynamic therapy. In the photodynamic therapy ofcancer, dye compounds are administered to a tumour-bearing subject.These dye substances may be taken up, to a certain extent, by thetumour. Upon selective irradiation with an appropriate light source thetumour tissue is destroyed via the dye mediated photo-generation ofspecies such as singlet oxygen or other cytotoxic species such as freeradicals, for example hydroxy or superoxide. Most biological studies onPc compounds related to PDT have been conducted with water solublesulfonated metallo-phthalocyanines as described by I. Rosenthal,Photochem. Photobiol. 53(6), 859-870, 1991. Methods for synthesizingthese compounds often results in mixtures of compounds containing avariety of isomers and/or different degrees of sulfonation.

[0061] Ideally compounds for use as photosensitizers in PDT have some orall of the following characteristics: solubility; high quantum yield ofreactive species; low toxicity; high absorption coefficients, preferablyin the red or near infra red of the spectrum; selective accumulation inthe tumour.

[0062] The reason why absorption in the red-region of the EM spectrum isdesirable is that red light shows greater penetration than light ofshorter wavelengths. Such sensitisers can be irradiated e.g. with laserlight, or from other non-laser sources e.g. tungsten halogen light. Thecompounds of the present invention are particularly advantageous in thisregard because of their spectral properties, their ability to form highconcentrations of dimers which fluoresce, and their solubility.Preferred compounds have Zn, Ru or Al as their metal centre, since thesehave previously been shown (in other PCs) to be effective generators ofsinglet oxygen.

[0063] One aspect of the present invention provides a pharmaceuticalcomposition comprising a compound of the invention (e.g Formula VIwherein M is Zn or Ru) in a mixture or in association with apharmaceutically acceptable carrier or diluent.

[0064] Also embraced is use of such a compound in the preparation of amedicament, preferably a medicament for treatment against cancer, mostpreferably for the treatment of a mammal having a tumour susceptible tophotodynamic treatment.

[0065] In a further aspect, the invention also includes a method oftreatment of a mammal having a tumour susceptible to photodynamictreatment wherein the mammal is administered an effective dose of acompound of formula I or a pharmaceutically acceptable salt form thereofand the tumour is subjected to suitable electromagnetic radiation.

[0066] The compounds described by the present invention may be inducedto act as a photosensitizers by incident electromagnetic radiation of asuitable wavelength. Preferably, the electromagnetic radiation issomewhere in the range ultra-violet to infra-red, even more preferablyit is in the range visible to red to near infra-red.

[0067] The pharmaceutical compositions may be formulated according towell-known principles and may desirably be in the form of unit dosagesdetermined in accordance with conventional pharmacological methods. Theunit dosage forms may provide daily dosage of active compound in asingle dose or in a number of smaller doses. Dosage ranges may beestablished using conventional pharmacological methods and are expectedto lie in the range 1 to 60 mg/kg of body weight. Other active compoundsmay be used in the compositions or administered separately, orsupplemental therapy may be included in a course of treatment for apatient. The pharmaceutical compositions may desirably be in the form ofsolutions of suspensions for injection or in forms for topicalapplication including application in for example the oral cavity.Application in other cavities is also possible. Suitable carriers anddiluents are well known in the art and the compositions may includeexcipients and other components to provide easier or more effectiveadministration.

[0068] Following administration to the patient, photodynamic therapy maybe carried out in a conventional manner, using light sources anddelivery systems that are known in the art, for example, see Phys. Med.biol. (1986), 31, 4, 327-360.

[0069] Enhanced positioning of the compounds of formula I in relation totreating tumours may be achieved. For example, the compounds of thepresent invention may be combined with other chemical moieties.

[0070] Thus a further aspect embraces compositions comprising suchcompounds plus a targeting molecule (e.g. an antibody) which may be partof a binding pair, the other member of the pair being located orconcentrated in the target site (e.g. an antigen associated with atumour). A particular compound could be combined, for example, bychemical attachment, with an antibody tailored to attach itself to thetumour site. Antibodies as prepared from cultured samples of the tumour.Examples include P.L.A.P. (Placental Alkaline Phosphatase), H.M.F.G.(Hunan Milk Fat Globulin), C.E.A. (Carcino Embryonic Antibody), H.C.G.(Human Chorionic Gonadotrophin).

[0071] Other targeting molecules may include lectins, protein A, nucleicacids (which bind complementary nucleic acids) etc.

[0072] Further possible uses of Pcs (as photosensitizers) include use asanti-virals in blood-banks or insecticides.

[0073] LCDs

[0074] It is well known that some phthalocyanine compounds exhibitliquid crystalline behaviour.

[0075] The majority of known liquid crystalline compounds have agenerally rod-shaped molecular structure and are often characterised bynematic and/or smectic mesophases. There are, however, a number of knowncompounds which are characterised by a generally disc-like molecularstructure. These compounds are termed discotic compounds, which can becharacterised by discotic nematic or columnar mesophase(s).

[0076] Discotic compounds can be based on a number of “cores”, e.g.benzene, truxene, metallophthalocyanine, phthalocyanines andtriphenylene.

[0077] Certain compounds of the present invention e.g. Ni, Cu, Co and 2Hcontaining compounds, have been demonstrated to exhibit columnarmesophases.

[0078] Guillon et al Mol. Cryst Liq. Cryst.; 1985, vol. 130. pp223-229,discuss columnar mesophases from metallated and metal free derivativesof phthalocyanine in which the phthalocyanine is substituted on thebenzene rings with various groups all of which are attached to thephthalocyanine core via a CH₂ unit.

[0079] Piechocki and Simon, New Journal of Chemistry, vol. 9, no 3,1985, pp159-166, report the synthesis of octa-substituted phthalocyaninederivatives forming discotic mesophases. The side chains are linked tothe phthalocyanine core via a CH₂ unit.

[0080] Most liquid crystal compounds are known as thermotropic liquidcrystal compounds. Thermotropic liquid crystals exist in dependence ofthe temperature in certain temperature intervals. In some cases whendifferent substances are mixed together with a solvent the mixture canexhibit different phases not only as the temperature is changed, butalso as the concentration of the solute is changed. When the liquidcrystal phase is dependent on the concentration of one component inanother it is called a lyotropic liquid crystal. The easiest way to makea lyotropic liquid crystal mixture is to start with a molecule thatpossesses end groups with different properties For example one end couldshow an affinity for water and the other end tends to exclude water.Molecules which possess both a hydrophilic group and a part which is ahydrophobic group can display characteristics of both classes, thereforethey are called amphiphilic molecules.

[0081] Lyotropic liquid crystals have numerous potential applicationsincluding detergents, the recovery of oil from porous rocks and in thefood industry, providing they are sufficiently non-toxic, for example asfood emulsifiers. There may also be medical applications for lyotropicliquid crystal systems. For example, amphiphilic materials could help tomake drugs more soluble in the blood.

[0082] For a review of phthalocyanine thermotropics, see Simon andBassoul in Phthalocyanines, Properties and Applications, Ed., C. C.Leznoff and A. B. P. Lever, V.C.H. Publishers 1992, p227.

[0083] Liquid Crystal Devices

[0084] One aspect of the invention includes use of the compounds ofFormula I, and use of mixtures including Formula I, in a liquid crystaldevice. Typically such devices include linear and non-linear electrical,optical and electro-optical devices, magneto-optical devices, anddevices providing responses to stimuli such as temperature changes andtotal or partial pressure changes. The devices themselves form a furtheraspect of the present invention.

[0085] A typical example of the use of a compound of Formula I in aliquid crystal material and device embodying the present invention willnow be described with reference to FIG. 4. The liquid crystal deviceconsists of two transparent plates, 1 and 2, in this case made fromglass. These plates are coated on their internal face with transparentconducting electrodes 3 and 4. An alignment layer 5, 6 is introducedonto the internal faces of the cell so that a planar orientation of themolecules making up the liquid crystalline material will beapproximately parallel or at a small angle to the glass plates 1 and 2.For some types of display the plane of the molecules is approximatelyperpendicular to that of the glass plates, and at each glass plate thealignment directions are orthogonal. The electrodes 3, 4 may be formedinto row and column electrodes so that the intersections between eachcolumn and row form an x, y matrix of addressable elements or pixels. Aspacer 7 e.g. of polymethyl methacrylate separates the glass plates 1and 2 to a suitable distance e.g. 2 microns. Liquid crystal material 8is introduced between glass plates 1, 2 by filling the space in betweenthem. The spacer 7 is sealed with an adhesive 9 in a vacuum using anexisting technique. Polarisers 10, 11 are arranged in front of andbehind the cell. For some devices, only one or even no polarisers arerequired.

[0086] The device may operate in a transmissive or reflective mode. Inthe former, light passing through the device, e.g. from a tungsten bulb,is selectively transmitted or blocked to form the desired display. Inthe reflective mode a mirror (12) is placed behind the second polariser11 to reflect ambient light back through the cell and two polarisers. Bymaking the mirror partly reflecting the device may be operated both in atransmissive and reflective mode.

[0087] The alignment layers 5,6 have two functions one to aligncontacting liquid crystal molecules in a preferred direction and theother to give a tilt to these molecules—a so called surface tilt—of afew degrees typically around 4E or 5E. The alignment layers 5, 6 may beformed by placing a few drops of the polyimide onto the cell wall andspinning the wall until a uniform thickness is obtained. The polyimideis then cured by heating to a predetermined temperature for apredetermined time followed by unidirectional rubbing with a rollercoated with a nylon cloth.

[0088] Laser Addressed Applications

[0089] Some phthalocyanines also absorb radiation in the far-red to nearinfra-red regions of the electromagnetic spectrum. Compounds whichabsorb strongly at wavelengths of laser light can in principle beexploited as guest dyes dissolved in liquid crystalline host materialsin a laser addressed system.

[0090] Materials have been proposed for laser addressed applications inwhich laser beams are used to scan across the surface of the material orleave a written impression thereon. For various reasons, many of thesematerials have consisted of organic materials which are at leastpartially transparent in the visible region. The technique relies uponlocalised absorption of laser energy which causes localised heating andin turn alters the optical properties of the otherwise transparentmaterial in the region of contact with the laser beam. Thus as the beamtraverses the material, a written impression of its path is left behind.One of the most important of these applications is in laser addressedoptical storage devices, and in laser addressed projection displays inwhich light is directed through a cell containing the material and isprojected onto a screen. Such devices have been described by Khan Appl.Phys. Lett. Vol. 22, p 111, 1973; and by Harold and Steele inProceedings of Euro display 84, pages 29-31, September 1984, Paris,France. in which the material in the device was a smectic liquid crystalmaterial. Devices which use a liquid crystal material as the opticalstorage medium are an important class of such devices. The use ofsemiconductor lasers, especially Ga_(x)Al_(1-x)As lasers where x is from0 to 1, and is preferably 1, has proven popular in the aboveapplications because they can provide laser energy at a range ofwavelengths in the near infra-red which cannot be seen and thus cannotinterfere with the visual display, and yet can provide a useful sourceof well-defined, intense heat energy. Gallium arsenide lasers providelaser light at wavelengths of about 850 nm, and are useful for the aboveapplications. With increasing Al content (x<1), the laser wavelength maybe reduced down to about 750 nm.

[0091] One of the main problems associated with the use of the abovematerials is that it has proved difficult to provide materials which aretransparent in the visible region and yet are strong absorbers in eitherthe UV or IR region, preferably in the near-IR region. The use of dyeswithin these materials can provide strong absorption at certainwavelengths, but few dyes are transparent in the visible region and manyare insoluble in the type of materials used for laser addressedapplications. EP-A-0155780 discloses a group of metal and metal-freephthalocyanines which have been used as infra-red absorbing dyes for anumber of applications. These phthalocyanines contain from 5 to 16peripheral organic substituent groups that are linked to thephthalocyanine through sulphur, selenium, tellurium, nitrogen or oxygenatoms. However, very few of the groups disclosed absorb infra-redradiation strongly at or near the wavelength of a gallium arsenide laser(850 nm). This problem also applies to a further group of infra-redabsorbing phthalocyanines disclosed in EP-A-0134518. This further groupconsists of naphthalocyanines which are peripherally substituted withalkyl groups and centrally substituted with a metal atom or a chloride,bromide or oxide thereof. Materials Science II/1-2, 1976 pp 39-45discloses the synthesis of octamethoxyphthalocyanines but these areinsoluble in organic solvents and as such are unsuitable for acting asdyes in liquid crystalline solvents for laser addressed systems. Variousof the compounds of the present invention are particularly suitable forthis application owing to their high solubility and the retention ofhigh absorbance at appropriate wavelengths even at high concentrations.The absorption maxima may be controlled by altering the central atom, orby use of additives (e.g. metal salts) or other agents to (e.g. pyridineto decomplex ZnAzaPc).

[0092] Optical Recording Media

[0093] For corresponding reasons to those discussed above, the compoundsof the present invention will be suitable for use in optical recordingmedia. Typically the phthalocyanine will absorb in the near-infrared. Inorder to make an optical recording media using a near-infrared absorber,the near-infrared absorber may be coated or vacuum-deposited onto atransparent substrate. European patent application EP 0 337 209 A2describes the processes by which the above optical-recording media maybe made. Further the materials described in EP 0 337 209 A2 are usefulin near-infrared absorption filters and liquid crystal display devices,as are the compounds described by the current invention. As described inEP 0 337 209 A2, display materials can be made by mixing a near-infraredabsorber of formula I with liquid crystal materials such as nematicliquid crystals, smectic liquid crystals and cholesteric liquidcrystals. The compounds of the current invention may be incorporatedinto liquid crystal panels wherein the near-infrared absorber isincorporated with the liquid crystal and laser beam is used to write animage. Mixtures of phthalocyanines of the current invention may be mixedwith liquid crystal materials in order to be used in guest-host systems.GB 2,229,190 B describes the use of phthalocyanines incorporated intoliquid crystal materials and their subsequent use in electro-opticaldevices.

[0094] The properties of spin coated films of compounds of the presentinvention are discussed hereinafter. Such spin coated films may beuseful in the production of optical recording media, and also insensors.

[0095] Sensors

[0096] Films of Pcs of the prior art have been used for as the activecomponent in conductometric and optical based sensors. They may alsohave utility as selective gas sensors (e.g. for N₂), as demonstrated bythe alteration in spectral properties which occurs in the presence ofparticular gasses e.g. HCl (see Figures below).

[0097] Langmuir-Blodgett (LB) Films

[0098] The materials of the current invention may also be incorporatedin Langmuir-Blodgett (LB) films. LB films incorporating phthalocyaninesof the current invention may be laid down by conventional and well knowntechniques, see R. H. Tredgold in ‘Order in Thin Organic Films’,Cambridge University Press, p74, 1994 and references therein. Generallyan LB film is prepared by depositing a monolayer of a surface-activematerial onto a water surface; this may be done using well establishedtechniques. The molecules of the surface active material align in themonolayer, the hydrophilic ends remaining in the water, and thehydrophobic end projecting out of the surface. By other known techniquesthis monolayer may be transferred essentially intact onto the surface ofa solid substrate and further monolayers deposited on the layer on thesubstrate to form a film, i.e. an LB film.

[0099] LB films including compounds of the current invention may be usedas optical or thermally addressable storage media.

[0100] Molecular Wires

[0101] The compounds of the current invention may also be used asmolecular wires, see R. J. M. Nolte et al, Angew, Chem. Int. Ed. Eng.,vol. 33, part 21, page 2173, 1994.

[0102] Photonic Devices

[0103] It is known that some phthalocyanines are excellent generators ofthird order non-linear optical effects and thus show promise for use inphotonic devices including all-optical switches and computers, seeBredas, Adant, Tackx Persoons and Pierce, Chem. Rev., 94, p243, 1994.The materials of the present invention may show such effects and be usedin such devices. In particular the distortion of the delocalised Bsystem of the AzaPc which may be induced by the pyridine ring may beexpected to produce novel properties as compared with prior art PCs usedfor this purpose.

[0104] Redox Applications

[0105] The compounds of the present invention allow for electronicinteraction of substituents with the Azaphthalocyanine ring. The redoxproperties of the Azaphthalocyanines described by the current inventionmay be easily modified by the altering the identity of the varioussubstituents. The compounds described by the current invention aretherefore useful in any one or more of the following: electrocatalysis,photocatalysis, photovoltaics (e.g. solar cells), electric conduction,photoconductivity and electrochromism and other applications whichexploit redox properties.

[0106] Polyelectrolytes

[0107] Polyethylene oxides can complex alkali metal ions, for exampleLi+ and have been used as polyelectrolytes in solid state batteryapplications, see Charadame in ‘Macromolecules’, ed. Benoit and Rempp,Pergamon press, New York, 1982, p226. The compounds of the invention mayalso be useful as polyelectrolytes, they are able to stabilise charge,therefore there exist a number of applications within batterytechnology.

[0108] Further aspects of the invention:

[0109] As well as use in the methods described above, in a furtheraspect of the invention there is a disclosed a method of preparing thecompounds of the present invention, substantially as describedhereinafter.

[0110] Dimers or higher oligomers comprising or consisting of thecompounds of the present invention are also embraced within its scope.Particularly embraced are “edge-to-face” dimers, including mixed dimersformed between one compound of the present invention and another Pc orAzaPc.

[0111] It may be advantageous to polymerise certain of the compoundsdescribed by the current invention. Polymerised phthalocyanines may beused in, for example, LB films. There are numerous ways by which thephthalocyanine compound may be polymerised. Polymerisation may beeffected via one or more of the positions R_(n) or R_(p) as described informula I of the current invention or via the central metal atom ormetal compound, or polymerisation may be realised by a combination ofthe above methods. An example of a suitable phthalocyanine substituentwhich may be used to effect polymerisation is an unsaturated substituentsuch as an alkene group.

[0112] Main chain or side chain liquid crystal polymers may also be madeusing the compounds of the present invention, or metal-linked liquidcrystal polymers.

FIGURES

[0113]FIG. 1(a) shows Pc

[0114]FIG. 1(b) shows Formula I

[0115]FIG. 1(c) shows Formula II

[0116]FIG. 1(d) shows Formula III

[0117]FIG. 1(e) shows Formula IV

[0118]FIG. 1(f) shows Formula V

[0119]FIG. 1(g) shows Formula VI

[0120]FIG. 1(h) shows:

[0121] Top. 250-800 nm spectrum of 1a as a solution in cyclohexane at1.46×10⁻⁶M; λ_(max) 710 nm (ε 1.36×10⁵). 687 nm (ε 0.95×10⁵). Insetspectrum (scale not shown) shows the Q-band absorption at 1.46×10⁻⁴M;λ_(max) 709 nm (ε 6.23×10⁴), 687 nm (ε 5.85×10⁴), 652 nm (ε 4.33×10⁴).

[0122] Middle, as above but for 1b at 1.04×10⁻⁶M; λ_(max) 694 nm (ε1.16×10⁵), 679 nm (ε 1.17×10⁵). Inset spectrum, Q-band absorption at1.04×10⁻⁴M: λ_(max) 690 nm (ε 5.61×10⁴), 679 nm (ε 6.15×10⁴), 643 nm (ε4.27×10⁴).

[0123] Bottom, as above but for 1c at 1.24×10⁻⁶M; λ_(max) 716 nm (ε0.86×10⁵). Inset spectrum, Q-band absorption at 1.24×10⁻⁴M; λ_(max) 715nm (ε 1.25×10⁵), 679 nm (ε 0.75×10⁵).

[0124]FIG. 2

[0125] Transmission electron micrograph of 1b as a THF gel on a carboncoated copper grid. The field of view is 453×294 nm.

[0126]FIG. 3

[0127] The visible region spectra of spin coated films of 1a (FIG. 3a),1b (FIG. 3b) and 1c (FIG. 3c). FIG. 3d shows the film of 1 c afterexposure of HCl vapour. Within 30 days after exposure to HCl, the filmgives a spectrum the same as that in FIG. 3c.

[0128]FIG. 4

[0129] A liquid crystal device as described in Example 4.

[0130]FIG. 5

[0131] Some of the compounds of the present invention which wereproduced as described in Example 1.

[0132]FIG. 6

[0133] A putative mixed (“edge to face”) dimer complex of the presentinvention.

[0134]FIG. 7

[0135] Scheme 1, showing phase transitions determined by DSC and opticalmicroscopy. Enthalpy data were determined by DSC at a heating/coolingrate of 10° C. min⁻¹. K and K₁ refer to crystal phases. The highertemperature mesophase for 1 a and 1 b appears as a fan texture whenviewed through a polarised light microscope, characteristic of acolumnar mesophase with hexagonal cross sectional symmetry in which thecolumns are disordered; ie D₂. The lower temperature mesophase shows aneedle type texture comparable with that assigned elsewhere to a secondD₁ mesophase within the octaalkylphthalocyanine series.

EXAMPLES Example 1 Preparation of Compounds of the Present Invention

[0136] Briefly, the novel macrocyclic derivative Formula VI, wherein Mwas 2H (designated 1 a) was obtained by reaction of 3,4-dicyanopyridinewith excess 3,6-dioctylphthalonitrile⁹ under basic (lithium pentyloxide)conditions. Following conventional workup, 1 a (10%) was separatedchromatographically from the principal by-product,1,4,8,11,15,18,22,25-octaocrylphthalocyanine.⁹

[0137] The compounds 81 to 88 shown in FIG. 5 were generated from themetal-free compound 80 (=1a) as exemplified by the Cu, Zn and Niderivatives described below.

[0138] Preparation of1,4,8,11,15,18-(hexaoctyl)tribenzo-3,4-pyrdinoporphyrazine

[0139] In a typical procedure, 3,6-dioctylphthalonitrile (3.17 g, 9mmol) and 3,4-dicyanopyridine (0.13 g, 1 mmol) in dry pentan-1-ol (30ml) were heated under reflux with stirring and lithium metal (0.2 g) wasadded slowly in small portions. The solution turned an intense greencolour immediately and reflux was continued for 6 hours, then themixture was allowed to cool to room temperature and glacial acetic acid(50 ml) was added and stirring continued for 30 minutes. The solventswere removed under reduced pressure and the mixture washed onto a filterwith methanol (500 ml) to remove non-phthalocyanine impurities, the restof which were left on the filter when the Pcs were taken up in THF. Thesolvent was removed under reduced pressure and the mixture was separatedusing column chromatography over silica gel. The first green fractioncontained only metal-free 1,4,8,11,15,18,22,25-octaoctylphthalocyanineusing as eluent light petroleum. The next green fraction was collected,eluent THF, and further purified by column chromatography over silicagel, eluent cyclohexane-THF (9:1) and recrystallised from THF-methanolto afford 1,4,8,11,15,18-(hexaoctyl)tribenzo-3,4-pyridinoporphyrazine asa blue solid (125 mg, 10% based on 3,4-dicyanopyridine). Mp 142° C.(K-D), 242EC (D-I); FAB-MS (LSIMS) m/z 1188. (Found: C, 79.54; H, 9.55;n, 10.65. C₇₉H₁₁₃N₉ requires: C, 79.82; H, 9.58; n, 10.60). ν_(max)(DCM)/cm⁻¹: 3285 (NH) and 1600 (aromatic); δ_(H) (270 MHZ: C₆D₆): −2.17(br s, 2H), 0.85-0.96 (m, 18H), 1.20-1.95 (m, 60H), 2.2-2.5 (m, 12H),4.10 (br s, 4H), 4.43 (M, 4H), 4.54 (m, 4H), 7.65-7.8 (m, 4H), 7.86 (s,2H), 8.53 (d, 1H), 9.14 (d, 1H), 10.35 (s, 1H); λ_(max)(cyclohexane)/nm: 328, 687 and 710. The third fraction to be collectedwas obtained using cyclohexane-THF (2:1) as eluent and recrystallisedfrom THF-methanol to afforddi-3,4-pyridino-1,4,8,11-(tetraoctyl)dibenzo-porphyrazine as a dark bluesolid (5 mg, 1% based on 3,4-dicyanopyradine). Mp 250EC (K-D), 326(D-I); FAB (LSIMS) m/z 966; (Found: C, 77.25; H, 8.53; N, 14.24C₆₂H₈₀N₁₀ requires: C, 77.14; H, 8.35; N, 14.51). δ_(H) (270 MHz; C₆D₆;50EC): −4.35-−3.83 (t, 211), 0.95 (t, 12H), 2.15-2.41 (m, 8H), 3.94 (m,4H), 4.20 (m, 4H), 7.59-7.74 (m, 4H), 8.19-8.30 (m, 2H), 8.96-9.03 (m,2H), 10.04-10.15 (t, 2H), λ_(max) (cyclohexane)/nm: 324, 669, 705.

[0140] Preparation of Copper1,4,8,11,15,18-(hexaoctyl)tribenzo-3,4-pyridinoporphyrazine

[0141] In a typical procedure, copper(II) acetate (0.2 g) was added to astirred solution of1,4,8,11,15,18-(hexahexyl)tribenzo-3,4-pyridinoporphyrazine (70 mg) inpentan-1-ol (20 ml) and heated under reflux for 90 minutes. The solventwas removed under reduced pressure and the residue purified using columnchromatography over silica gel using as eluent cyclohexane-THF (5:1) andrecrystallised from THF-methanol to afford copper1,4,8,11,15,18-(hexaoctyl)tribenzo-3,4-pyridinoporphyrazine as a bluesolid (48 mg, 65%). Mp 134° C. (K-D), 319° C. (D-I); FAB (LSIMS) m/z1249; (Found: C, 75.84: H, 9.00; N, 9.90. C₇₉H₁₁₁N₉Cu requires: C,75.89; H, 8.95; N, 10.08). λ_(max) (cyclohexane)/nm: 325, 343 629, 649,686, 701.

[0142] Preparation of Nickel and Zinc Derivatives

[0143] The Ni derivative (designated 1b) or Zn derivative (designated1c) were produced by reactions of 1a with nickel acetate and zincacetate in refluxing pentanol generated 1b (53%) and 1c (78%). Each gavea satisfactory elemental analysis and low resolution FAB-ms as follows:Found: C, 79.54; H, 9.55; N, 10.65; C₇₉H₁₁₃N₉ requires: C, 79.82: H,9.58; N, 10.60. 1b, Found: C, 76.10; H, 9.00; N, 9.95; C₇₉H₁₁₁N₉Nirequires: C, 76.18; H, 8.98; N, 10.12. 1c, Found: C, 75.68; H, 8.78; N,9.95; C₇₉H₁₁₁N₉Zn requires: C, 75.78; H, 8.94; N, 10.07.

[0144] All three compounds (1a, 1b, 1c) showed good solubility insolvents such as THF, toluene, cyclohexane and dichloromethane.

[0145] Compounds of the present invention based on a napthalocyaninestructure (i.e. azanapthalocyanines) can be prepared by methodsanalogous to those described above, in conjunction with the disclosureof Cammidge et al (1997) J Porphyrins Pthalocyanines 1:77-86.

Example 2 Spectra of the Compounds

[0146] The properties of the substitutedpyridino[3,4]-tribenzoporphyrazines, 1, prove to be highly dependentupon the atom(s) at the centre of the macrocycle and reflect theindividual compound's propensity for forming either Face-to-Faceassemblies or Edge-to-Edge complexes. The Q-band absorptions in thevisible region spectra of solutions of 1a (2H) and 1b (Ni) incyclohexane at ca. 1×10⁻⁶M are shown in FIG. 1. The two component Q-bandof 1a, top spectrum in FIG. 1, is similar to that of a metal-free Pc.The Q-band of 1b, the middle spectrum, is also split λ_(max) 694 and 679nm, differing from that of simple metallated Pcs but consistent with thelower symmetry of the system.¹⁰ Otherwise, the high extinctioncoefficients of the Q-bands, see legend to FIG. 1, and the very lowintensity absorptions to the blue are characteristic of Pc compoundswhich are essentially non aggregated. At high concentrations, however,Face-to-Face type aggregation becomes apparent, manifested by thecharacteristic enhanced absorption in the region 600 to 690 nm (see theinset spectra in FIG. 1) and the lower extinction coefficients of thelowest energy bands.

[0147] The zinc derivative, 1c, shows different behaviour. The spectrumof 1c in cyclohexane, the bottom spectrum in FIG. 1, and indichloromethane shows enhanced separation of the main Q-band componentsλ_(max) 716 and 675 nm, within a band envelope which is essentiallyinvariant over the concentration range ca. 1×10⁻⁷M. In particular,extinction coefficients remain high at the higher concentrations.Absence of Face-to-Face aggregation is signified by the lack ofsignificant absorption in the visible region to the blue of these mainbands. The gel permeation chromatogram obtained for elution of 1c as asolution in dichloromethane through PLgel 100A and 500A, 30 cm, 5 microncolumns and calibrated against polystyrene gives a peak molecular mass,Mp, of 2050 (M_(w) 1630 and M_(n) 1390). Elution of three modelphthalocyanine derivatives under the same conditions showed that the“polystyrene equivalent” molecular masses for these macrocycles areconsistently 20-25% lower than the actual molecular mass. Thus the Mpobtained for 1 c suggests that under the conditions of the GPCexperiment, the material has formed a dimeric complex.

[0148] Thus we assign the visible region spectrum of 1c, above, to adimeric species (or lower oligomeric species) arising fromintermolecular axial ligation of a pyridyl nitrogen of one macrocyclewith the zinc atom of a second, to form an Edge-to-Face complex. Insupport of this, we note that addition of pyridine or THF changes theband shape to one closely resembling that of non-aggregated 1b; this weattribute to disruption of the homoligated complex of 1c. Similarly,excitation of 1c (λ_(ex) 650 nm) as a solution in toluene at 1.2×10⁻⁵Mshows fluorescence emission at λ_(max) 731 nm. Addition of 100 Flpyridine raises the emission intensity by a factor of two and shifts theemission band to 720 nm. In contrast 1a under the same conditions showsλ_(em) 721 nm, essentially unchanged when pyridine is added.

[0149] Further confirmation of the formation of Edge-to-Face complexesby 1c was obtained by ¹H-NMR spectroscopy. The spectrum of 1c inbenzene-d₆ shows no signals downfield of δ 8.32. Upon addition ofpyridine-d₅, the spectrum simplifies and is very similar to that of 1a.In particular, the pyridyl protons of 1c now appear at 9.25, 9.43 and11.12 ppm. We believe it likely that higher oligomers may be present atthe higher solution concentrations used in the NMR experiment.

[0150] NMR spectroscopy of 1a (Ni derivative) at 1 mM suggests somedegree of edge-to-face structure, in addition to UV-VIS evidencesuggesting face-to-face structures which is discussed above.

Example 3 TEM

[0151] Transmission electron microscopy highlighted differences inpacking in the condensed states of 1a, 1b and 1c. A drop of a solutionof each compound in THF (2 mg per ml) was administered onto a coppergrid, blotted dry, and viewed through a JEOL 100CX Electron Microscopeas the solvent evaporated. FIG. 2 shows the micrograph obtained for 1b.It clearly shows the generation of a columnar structure, formallyanalogous to the “molecular wires” observed by Nolte et al.¹¹ for a morecomplex Pc derivative. Compound 1 a showed similar behaviour. The widthof the assembly depicted in FIG. 2 is ca. 15 times the approximatediameter of the individual molecules of 1b. In contrast, 1c forms adistinctly different structure, the micrograph showing an apparentlyfeatureless film with no evidence of column formation.

Example 4 LC Properties

[0152] The differences in the molecular packings in the condensed phaselead to different behaviour on heating and cooling. Thus, compounds 1aand 1b exhibit thermotropic columnar mesophases; polarised lightmicroscope shows a fan type structure on cooling from the isotropicliquid consistent with the hexagonal columnar mesophase exhibited byother non-peripherally alkyl-substituted Pcs.¹² Phase transition dataare reported in Scheme 1 (FIG. 7). In contrast, 1c does not exhibit amesophase during either heating of the solid sample or upon cooling fromthe liquid phase; this we attribute to the orthogonal packing ofadjacent molecules in the solid state and, presumably, in the liquidstate just prior to crystallisation.

Example 5 Spin Coated Films

[0153] Large area evaporated films were formulated by the spin coatingtechnique by administering a drop of solution of each compound in THF(ca. 2 mg in 0.5 ml) onto a glass slide rotating a 2000 rpm. Films soformed were transparent and showed no crystallites when viewed under anoptical microscope. Their visible region spectra are shown in FIGS. 3a-3c. Those for the films of 1a and 1b are closely similar to the spectraof films of metal-free and nickel1,4,8,11,15,18,22,25-octa-octylphthalocyanines respectively^([12])whereas the film spectrum for 1c, FIG. 3c, is similar to its solutionphase spectrum, albeit blue-shifted by ca. 10 nm. Exposure of the latterfilm to pyridine vapour did not change the spectrum. However, theassembly became disrupted upon exposure to HCl vapour. The new spectrumis shown in FIG. 3d. Within 30 days the original spectrum was recovered,implying that the response to HCl is fully reversible and the moleculesreassemble to give the intermolecular complex.

[0154] In conclusion, we have identified a phthalocyanine typemacrocycle whose molecular packing is governed by the central metal ion.Both Face-to-Face and Edge-to-Face packing has been identified. Thelatter is promoted by the propensity for zinc to undergo strong axialligation and columnar liquid crystal behaviour, otherwise inherentwithin the series, is inhibited. Nickel complexes may also undergo weakaxial ligation. However, 1b at UV/vis concentrations and in the liquidcrystal phases favours Face-to-Face structures in which the Ni(II)d⁸ ionis presumably in its favoured spin paired, square-planar four coordinatestate.

Example 6 An LCD Device

[0155] An example of the use of a compound of Formula I in a liquidcrystal material and device embodying the present invention will now bedescribed with reference to FIG. 4.

[0156] The liquid crystal device consists of two transparent plates, 1and 2, in this case made from glass. These plates are coated on theirinternal face with transparent conducting electrodes 3 and 4. Analignment layer 5, 6 is introduced onto the internal faces of the cellso that a planar orientation of the molecules making up the liquidcrystalline material will be approximately parallel or at a small angleto the glass plates 1 and 2. For some types of display the plane of themolecules is approximately perpendicular to that of the glass plates,and at each glass plate the alignment directions are orthogonal. Theelectrodes 3, 4 may be formed into row and column electrodes so that theintersections between each column and row form an x, y matrix ofaddressable elements or pixels. A spacer 7 e.g. of polymethylmethacrylate separates the glass plates 1 and 2 to a suitable distancee.g. 2 microns. Liquid crystal material 8 is introduced between glassplates 1, 2 by filling the space in between them. The spacer 7 is sealedwith an adhesive 9 in a vacuum using an existing technique. Polarisers10, 11 are arranged in front of and behind the cell. For some devices,only one or even no polarisers are required.

[0157] The device may operate in a transmissive or reflective mode. Inthe former light passing through the device, e.g. from a tungsten bulb,is selectively transmitted or blocked to form the desired display. Inthe reflective mode a mirror (12) is placed behind the second polariser11 to reflect ambient light back through the cell and two polarisers. Bymaking the mirror partly reflecting the device may be operated both in atransmissive and reflective mode.

[0158] The alignment layers 5, 6 have two functions one to aligncontacting liquid crystal molecules in a preferred direction and theother to give a tilt to these molecules—a so called surface tilt—of afew degrees typically around 4 or 5°. The alignment layers 5, 6 may beformed by placing a few drops of the polyimide onto the cell wall andspinning the wall until a uniform thickness is obtained. The polyimideis then cured by heating to a predetermined temperature for apredetermined time followed by unidirectional rubbing with a rollercoated with a nylon cloth.

Example 7 Gas Sensor

[0159] In another example a layer of liquid crystal material is exposedto a gas to provide a gas sensor.

Example 8 Mixed Dimers

[0160] Upon introduction of 1.0 eq of Zn1,4,8,11,15,18,22,25-octahexylphthalocyanine (designated 6Zn in FIG. 6)into the ¹H NMR solution of compound 80 in C₆D₆ there was no signalobserved downfield of δ8.05. Prior to this addition the signals for thepyridyl protons appeared 8.53, 9.14, 10.35 ppm. Instead of three signalsrepresenting the methylene protons next to the ring, four signalsappear. This seems to suggest that on formation of a dimeric complexthrough the coordination of the pyridine unit of compound 80 to the zinccentre of the 67Zn; the ring current of the 6Zn shields two methyleneprotons of 80 to a significant degree causing an upfield shift of 0.43ppm. The N—H proton of 80 is shifted downfield by 0.55 ppm.

REFERENCES

[0161] 1. Phthalocyanines—Properties and Applications, eds. Leznoff andLever, VCH Publishers, New York, 1989.

[0162] 2. Cook, in Spectroscopy of New Materials, eds. Clark and Hester,Wiley, Chichester, 1993,p.87.

[0163] 3. Simon and Bassoul, in Phthalocyanines—Properties andApplications, eds. Leznoff and Lever, VCH Publishers, New York, 1993,vol.2,p.223.

[0164] 4. See, for example, Mason et al. J.Chem.Soc., Dalton Trans.1979,676.

[0165] 5. Pomogailo and Wöhrle, in Macromolecule-Metal Complexes, eds.Ciardelli et al. Springer, Berlin-Heidleberg, 1996, p.11; Hanack andLang, Adv. Mater. 1994,6,819.

[0166] 6. Eg. Shachter et al., J.C.S.Chem.Commun. 1988, 960; Fleischerand Shachter, Inorg.Chem., 1991,30,3763; Hunter and Sarson,J.C.S.Chem.Commun., 1994, 33,2313; Funatsu et al., Chem.,Lett.,1995,765; Anderson et al., Angew.Chem.Int.Ed.Engl., 1995,34,1096;Alessio et al., J.C.S.Chem.Commun., 1996,1411-1412.

[0167] 7. Linstead et al., J.Chem.Soc., 1937,911.

[0168] 8. Yokote and Shibamiya, Kogyo Kagaku Zasshi, 1959,62,224.Chem.Abs. 1961,24019; Yokote et al., Kozyo Kagaku Zasshi, 1964, 67, 166.Chem.Abs. 61, 3235; Yokote et al., Yuki-Gosei Kagaka Kyokaishi1965,23,151. Chem.Abs. 71,32931h; Sakamoto and Shibamiya,J.Japn.Soc.Colour Material, 1985,58,121; Sakamoto and Shibamiya,J.Japn.Soc.Colour Material, 1986,59,517.

[0169] 9. Chambrier et al., J.Mater.Chem., 1993,3,841.

[0170] 10. cf. Kobayashi et al., J.Am.Chem.Soc., 1996,118,1073; Cook andJafari-Fini, J.Mater.Chem., 1997,7,5.

[0171] 11. van Nostrum et al., Angew.Chem., Int.Ed.Engl., 1994,33,2173;van Nostrum et al., J.Am.Chem.Soc., 1995,117,9957.

[0172] 12. Cherodian et al., Mol.Cryst.Liq.Cryst., 1991,196,103.

1. A compound of Formula I (FIG. 1(b)) wherein: M is selected from: a metal atom; a metal compound; 2H whereby one H is bonded to each of the two nitrogen atoms depicted as being bonded to M (positions 29 and 31 shown) and wherein: one or more of the Q groups is selected from: formula II (FIG. 1(c)) or formula III (FIG. 1(d)), with the remaining Q groups each being formula IV (FIG. 1(e)): wherein: R₃₃ and R₃₄ are independently selected from: H or methyl R₃₅ is selected from: H; C₁ to C₄ alkyl; C₂ to C₄ alkenyl: methoxy: butoxy; propoxy; NH₂; NH—(C₁ to C₄ alkyl); N—(C₁ to C₄ alkyl)₂, S—(C₁ to C₄ alkyl), each R_(n) and R_(p) group is independently selected from: C₁ to C₃₂ alkyl; C₂ to C₃₂ alkenyl; X—O—Y; X-phenyl X²COOX¹; X²CONR¹R¹¹; H; halide wherein: X and X² are independently selected from: a chemical bond; —(CH₂)_(n)— wherein n is an integer from 1 to 32; —(CH₂)_(a)—CH═CH(CH₂)_(b) where a and b are independently selected from integers 0-32 and a+b totals
 32. X¹ and Y are independently selected from: C₁ to C₃₂ alkyl; C₂ to C₃₂ alkenyl; H R¹ and R¹¹ are independently selected from: H; C₁ to C₃₂ alkyl; C₂ to C₃₂ alkenyl; —(CH₂)_(n)— with the proviso that where more than one Q is Formula II with the remaining Q group being Formula IV, at least one group independently selected from: R_(33,) R₃₄, R₃₅, an R_(n) group, an R_(p) group, is not H.
 2. A compound as claimed in claim 1 having formula V (FIG. 1(f)), Wherein: M is selected from: a metal atom, a metal compound: 2H whereby one H is bonded to each of the two nitrogen atoms depicted as being bonded to M (positions 29 and 31 shown) R₃ is H or methyl R₁ and R₄ are independently selected from: H; C₁ to C₄ alkyl; C₂ to C₄ alkenyl; methoxy; butoxy; propoxy; NH₂; NH—(C₁ to C₄ alkyl); N—(C₁ to C₄ alkyl)₂, S—(C₁ to C₄ alkyl), R₈ to R₂₅ are the same or different and are independently selected from: C₁ to C₃₂ alkyl; C₂ to C₃₂ alkenyl; X—O—Y; X-phenyl X²COOX¹; X²CONR¹R¹¹; H; halide and wherein X, X², X¹, Y, R¹ and R¹¹ are as defined in claim
 1. 3. A compound as claimed in claim 1 or claim 2 wherein all non-peripheral R groups other than those attached to pyridyl nuclei are selected from: H; alkyl containing up to 32; up to 20; between 4-14; or between 8-12 C atoms where 1 or more adjacent CH₂ groups may be replaced by O or a double bond, and the remaining R groups are all H.
 4. A compound as claimed in claim 3 wherein all non-peripheral R groups are H.
 5. A compound as claimed in any one of the preceding claims wherein all peripheral R groups other than those attached to pyridyl nuclei are selected from: alkyl containing up to 32; up to 20; between 4-14; between 8-12 C atoms, and the remaining R groups are all H.
 6. A compound as claimed in any one of the preceding claims wherein R_(33,) R₃₄, R₁ and R₃are H.
 7. A compound as claimed in any one of the preceding claims wherein R₃₅ and R₄ are electron donating groups independently selected from: O-alkyl, NH₂, NH-alkyl, N(alkyl)₂, alkyl, S-alkyl.
 8. A compound as claimed in any one of the preceding claims wherein those the alkyl groups present within R groups are straight chain alkyl.
 9. A compound as claimed in any one of the preceding claims wherein M is selected from: 2H; Ru, Ni, Pb, V, Pd, Co, Nb, Al, Sn, Zn, Cu, Mg, Ca, In, Ga, Fe, Eu, Lu and Ge.
 10. A compound as claimed in claim 9 wherein M is selected from: 2H; Zn; Cu; Co; Ru; and Ni.
 11. A compound as claimed in claim 10 having formula VI (FIG. 1(g)) wherein M is selected from: 2H; Zn; Ni.
 12. A compound as claimed in any one of the preceding claims which has an absorption maximum in the near infra-red.
 13. A compound as claimed in any one of the preceding claims which is soluble.
 14. A composition comprising a compound as claimed any one of the preceding claims.
 15. A pharmaceutical composition comprising a compound of any one of claims 1 to 13 in admixture with a pharmaceutically acceptable carrier.
 16. A compound of any one of claims 1 to 13 for use in PDT.
 17. A compound of any one of claims 1 to 13 for use in the preparation of a medicament.
 18. A compound as claimed in claim 16 or claim 17 wherein the PDT or the medicament is for the treatment of a mammal having a tumour susceptible to photodynamic treatment.
 19. A method of treatment comprising the step of exposing a compound as claimed in any one of claims 1 to 13 to laser radiation.
 20. Use of a compound of any one of claims 1 to 13 in an LC device.
 21. An LC device comprising two spaced walls each bearing electrode structures and treated on at least one facing surface with an alignment layer comprising a compound as claimed in any one of claims 1 to
 13. 22. An LC device as claimed in claim 21 which is an electro-optical display device.
 23. Use of a compound of any one of claims 1 to 13 in an optical recording medium.
 24. A method of storing or retrieving information comprising the step of exposing a compound as claimed in any one of claims 1 to 13 to laser radiation.
 25. An optical recording medium comprising a recording layer, said layer comprising a compound as claimed in any one of claims 1 to
 13. 26. An optical recording medium as claimed 25 wherein the compound is present as a spin coated film.
 27. An optical recording medium as claimed in claim 26 wherein the compound is a near infra-red absorber.
 28. Use of a compound of any one of claims 1 to 13 in a gas sensor.
 29. A method of detecting a gas in a sample comprising the step of exposing a compound as claimed in any one of claims 1 to 13 to the sample.
 30. A gas sensor comprising a compound as claimed in any one of claims 1 to
 13. 31. A gas sensor as claimed in claim 30 wherein the compound is present as a spin coated film.
 32. An LB film comprising a compound as claimed in any one of claims 1 to
 13. 33. A molecular wire comprising a compound as claimed in any one claims 1 to
 13. 34. Use of a compound as claimed in any one of claims 1 to 13 in a Photonic device.
 35. A Photonic device comprising a compound as claimed in any one of claims 1 to
 13. 36. Use of a compound as claimed in claimed in any one of claims 1 to 13 in any one of the following: electrocatalysis; photocatalysis; electric conduction; photoconductivity: electrochromism; a photovoltaic cell; a battery.
 37. Use of a compound as claimed in any one of claims 1 to 13 in the production of a dimer.
 38. A dimer or higher oligomer consisting of a compound as claimed in any one claims 1 to
 13. 39. A mixed dimer or higher oligomer comprising a compound as claimed in any one and a further Pc or Pc derivative.
 40. Use of a compound of any one of claims 1 to 13 in the production of a polymer.
 41. A polymer consisting of a compound as claimed in any one of claims 1 to 13 in polymerised form.
 42. An AzaPc essentially as described herein with reference to the accompanying Examples and Figures.
 43. A method of producing a compound as claimed in any one claims 1 to 13 essentially as described herein with reference to Example
 1. 